Recently, in electrical apparatuses, various resin molded articles have been used in housings and internal electrical system components. Electrical apparatuses include not only general household electric appliances and industrial electrical products, but also, for example, apparatuses that control electrical systems in vehicles such as automobiles, motorcycles and trucks, and resin molded articles are widely used in these apparatuses. As resin molded articles to be used in electrical apparatuses in vehicles, particularly apparatuses that are placed in engine rooms, those capable of resisting corona discharge caused by ignition coils etc. are required. That is, when a resin molded article is exposed to corona discharge, a dendroidal local failure called an electrical tree develops to reduce the life of the resin molded article, and such a situation must be prevented.
On the other hand, resins to be used in electrical apparatuses in vehicles are required to have heat resistance, flame retardancy and so on, and therefore polyarylene sulfide resins (hereinafter, also referred to as “PAS resins”) that have the required properties are suitably used. However, the PAS resin alone does not provide sufficient corona resistance, and various attempts have been made to impart corona resistance to resin molded articles (compositions) (see, for example, Patent Documents 1 to 3).
Patent Literature 1 discloses a material (biaxially oriented film) formed of a polyphenylene sulfide (hereinafter, also referred to as a “PPS resin”), the corona resistance of which is improved by ensuring that the content of sodium chloride is not more than 0.5% by weight.
Patent Literatures 2 and 3 each disclose a molded article (cable component, snow resistant ring) formed of a resin composition containing a PAS resin, a conductive carbon black, graphite and an epoxy group-containing α-olefin-based copolymer. This is intended to improve corona resistance as well as various properties such as heat resistance, weather resistance, flame retardancy, waterproofness, airtightness, toughness and soon by setting the volume resistivity of the resin composition to a proper value.